L ratings are required to be written on laser safety eyewear in Australia and Europe and is a measurement of how long the laser glasses can survive a direct hit from a particular laser. It requires that eyewear is labelled with protection levels that detail their damage thresholds, (e.g. 10600 D L5 (where L5 reflects a power density of 100 MegaWatt/m2 during a 10 seconds direct hit test at 10,600nm). The recomended scale numbers are shown in the below table.
Modes of Operation
Lasers operating at different modes have different power density characteristics and often different eyewear requirements.